text:
Do GA aircraft pilots use predefined routes (via GPS or DME/VOR vectoring) or methods such as GPS-direct/ VOR-to-VOR in UC airspace?
Example:
Flying from RIC to IAD, the most popular and "efficient" route is BENTLY -> CAVLR3:

However, you could more simply depart north out of the RIC Class-D, intercept the BROOKE VOR on the edge of the DC SFRA, and then accept the inevitable vectors from Potomac Approach to IAD:

While the time en-route and distance are only trivially shorter, it still illustrates my point: choosing to fly a "non-standard" route is both quicker and potentially easier (without a GPS, hitting the intersections is a more complicated procedure than "direct to BROOKE VOR").
From my training I understand that these airways are primarily used to organize air traffic to reduce risk of collision in uncontrolled airspace as well as to improve flow and organization in controlled.
Which methods (routes/airways vs direct GPS/VOR/DME nav) are more commonly employed by IFR and (vs?) VFR pilots?
Thank you!

Are you asking about small VFR flights or small IFR flights? VFR don't use predefined routes; they use visual reference. Small aircraft flying IFR will mostly be subject to the same rules regarding flight planning as large commercial flights.

@J.Hougaard VFR pilots don't have to use visual references for navigation. In fact victor airways are available to both VFR and IFR pilots and VFR pilots can choose to follow airways along a VOR route, it is a common part of VFR navigation training. I often use GPS direct routes when I can, but I'm more than capable of VOR navigation when flying VFR, or even dead reckoning.

So it seems that for both IFR and VFR, it's down to the preference of the pilot.
I guess then what I'm asking is, why would you choose to take a longer route w/ airways instead of a direct GPS method given the option, ATC's preference notwithstanding?
EDIT: This resource seems to answer this question precisely: https://bruceair.wordpress.com/2012/07/30/flying-and-filing-direct-v-airways/

Are you asking about a specific country (the US?) or jurisdiction, or is it a general question? That could change the answer. And this question is very similar.

In general. Also I did read that question but found the answer to be more geared towards how the airways work instead of which is used more preferentially.

So the answer to my question seems to be that for both VFR and IFR, assuming you have the appropriate equipment (e.g. GPS), flying direct has the benefits of

Saving time and fuel by trimming miles from long flights
Simplifying the creation of flight plans (lists of waypoints) in GPS navigators, especially units that don’t support entry of airway designations
Simplifying navigation in flight by reducing the number of turn points
Avoiding avoid major changes from a filed IFR flight plan when they receive their actual clearance from ATC.

while flying using established airways has the benefits of

Making it easier to track your progress on charts
Helping you remain aware of alternatives should you need to stop for fuel, accommodate passengers, avoid weather, or deal with a malfunction
Avoiding terrain/restricted airspace/obstacles

At the end of the day it seems to ultimately come down to what ATC clears you for, which is mostly dependent upon the nature of the area you're flying in/through based on traffic density and terrain/airspace complications (your planned route out of SFO is much more likely to be at the whims of ATC, compared to departing Jackson Hole). Filing plans which utilize SIDs and STARs should therefore feasibly be less prone to modification (my assumption) when departing/arriving at an airport, leaving your choice of direct vs. airways during the cruise portion of the flight more dependent upon terrain and other factors.

By definition, there are no defined airways or routes in uncontrolled airspace, so the answer to that question is no.

That is simply not true (at least in Europe).

I don't pretend to know a lot about the subject, but just from simply looking at CONUS sectionals, I can say your statement seems to be categorically false.

@Carlo Felicione is correct.  However,  most airpace in the U.S. is controlled airspace. (Class E) above 1200 FT AGL.  Very few sections of the U.S. have uncontrolled airspace to 14,500 FT MSL.


text:
Blunt noses subsonic drag - why a complete ellipse?
At subsonic speeds, blunt noses - both fuselage and airfoil - are good for two reasons:

the need to maintain attached flow at varying angles of attack.
it has less surface area for the volume, reducing skin friction.

TOP: 0 AoA/Cruise
| BOTTOM: extreme AoA, 20-30degrees, takeoff/landing
If the airflow had to flow over a ridge/point in scenario 2, instead of the smooth curve, flow separation would be more likely.
But things don't seem to add up.
Firstly, it's not like most airplanes - particularly airliners - fly at AoA beyond 20-30 degrees. At least not without high-lift devices. Am I correct? But on the rounded nose, there are surfaces smoothly curving all the way from 90 degrees! This seems to me like a useless increase in cruise drag.
Secondly, why push a blunt face ahead of you just to increase the volume a little, whem you can use a curve terminating at a point/ridge, as will be demonstrated below? If the surface area to volume ratio becomes so important, we can just sacrifice the fineness ratio and still have less drag, as the new nose creates less drag, right?
Would limiting the curvature to the max AoA limit for the aircraft, then terminating at a point, as in the image below, not keep the flow attached throughout the expected AoA range, while producing less drag? At the maximum AoA, the flow over the top of the shape encounters no "ridge" or "point", as it is parallel to the half-angle at the nose.

TOP: less drag is created at cruise
| BOTTOM: Flow remains attached at extreme AoA conditions.
What am I missing about the sharp nose? How and how much does it hurt performance? Why, after all this seemingly shown in the question, is it - aside from the radar - that big planes have round noses?
In short: I am claiming that an elliptical nose tipped with a triangle or cone of 20-30 degrees half-angle should be better than a pure ellipse for subsonic aircraft. Why am I wrong?

Does this answer your question? Why/when is the blunt nose better?

No it doesn't. I came here after reading it.

A ridge on the leading edge is a terrible idea for subsonic flight. That's how icing kills airplanes.

What you are missing is suction on that round nose which adds some thrust.
Granted, around that stagnation point there is a pressure region which also acts on a forward-facing surface, thus creating drag. But that region is small. Thanks to the curvature of the elliptic nose shape, air accelerates quickly out of this high pressure region. In order to follow the curved surface, the pressure has to fall below ambient on a still somewhat forward-facing area so the air is actively pulling the nose forward. No such suction can be expected on the straight contour of a pointed, cone-shaped nose.
The plot below only shows an airfoil, but flow around an elliptic nose is quite similar.

CPV plot from XFOIL, showing local pressure as arrows. Suction is pointing out, pressure into the contour. Length denotes difference to ambient pressure.

what does that diagram show - pressure or pressure gradient?

@ABJX Pressure. Suction is pointing out, pressure into the contour. Length denotes difference to ambient pressure.

wow........negative pressure even at the bottom......

what's that drooped nose-like thing at the nose?

@ABJX: That is just a bunch of arrow tips. They scale with arrow length (would be hard to do otherwise). The airfoil has a regular contour. And yes, suction at the bottom from the displacement effect is completely normal at lower angles of attack.

but that is soooooooo crazy for me, i mean that huge difference in pressure between the top of the nose and the bottom. could u somehow show me that foil but with negative AoA, just to get a better idea of the situation?

There is a stagnation point at the nose, where the airflow separates around it. As the aircraft attitude changes, it reduces drag if this stagnation point can move. Technically the explanation for this is a problem of three-dimensional flow, which is difficult to analyze. Intuitively the air "wants" to flow the most efficient way and fixing the stagnation point prevents that. There is an increase of pressure on the side of the point facing the incoming flow; the air has to turn harder to avoid it on that side, and that increases the local pressure. This is also destabilizing, so tail surfaces have to be larger. A round nose allows the stagnation point to move, in turn letting the air find the lowest-drag route.
Also, extending the nose uses more material, which increases skin drag, weight and cost.
Having said all that, these effects are small to trivial and many planes have had pointed noses - or pointed prop spinners - and not suffered unduly.

but why does the stagnation point have to move to reduce high AoA drag? besides, the extension can be used to store things, and surely the pointed shape reduces pressure drag.

OK, I have added a bit more detail.

Right. In your answer itself it says that some planes have had pointed noses without hurt. And now that I sort of get what you're saying with the stagnation point moving, it would still appear that the drag reduction at angle would not be significant. Also, what about airfoils? This also I was asking. Thanks for the answer though :)

Wait I just noticed: "There is a stagnation point at the nose, where the airflow separates around it" why is the airflow separating, especially since the flow over the low-pressure side is not turned at all over the sharp nosepoint in the high-AoA scenario shown above?

The airflow separates around it, not from it. There is a difference.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Is/why isn't the Antonov 124 to 225 wing upgrade method common?
I'm told that wing redesigns (edit: for tapered, swept wings) are difficult, so variants of a model often do with a common wing optimized for the middle member.
But then I read the following:

Based on Antonov's earlier An-124, the An-225 has fuselage barrel extensions added fore and aft of the wings. The wings also received root extensions to increase span.

That doesn't look so difficult. Of course, the wing root would be a new design, but we still get to keep the rest of the wing. Perhaps the flutter modes are less favorable......but wouldn't that be more or less inherent to higher spans?
So: Is/why isn't this method used to design variants or derivatives of large airliners?

I think you may be underestimating the effort that went into the wing root extensions. Sure it was probably easier than designing a whole new wing, but I doubt is was as simple as "drawing longer lines".

@FreeMan could be. I don't know, that's the point.

The Antonows you mentioned are quite a specialty freighter compared to other planes. Other planes, think of the commonly available jets of Airbus and Boing, need to fit certain geometric size ranges to allow their use with jet-bridges and other airport infrastructure. The Antonows generally do not dock on Terminals, thus, the may have more wingspan than other planes. Boing designed folding wing tips to maintain maximum on-ground wingspan for this reason. If your plane always loads/unloads out on the tarmac, you can affort to increase wing span.

With straight wings the root extension method is very common. Airplanes that come to mind are

Me-109 H (high altitude version with increased span)
Beech Twin Bonanza and Model 65 Queen Air (used the Bonanza wing from the engines out)
SB-10 (uses SB-9 wings stuck to a new carbon-epoxy center wing).

This is impractical with swept wings because of the strong twist and airfoil changes which are needed at the wing root to keep the isobars straight on the swept wings. The only way to increase an existing wing's size was used for the A340-500/600 by inserting a triangular section at mid-chord into the A340-200/300 wing which also allowed to increase its wingspan.

Source: Evolvability and design reuse in civil jet transport aircraft

but the 225 was swept? that was what interested me

@Abdullah: The An-124 doesn't have the wing twist and also not the increasing root chord of most other transport airplanes, also its maximum Mach number is only 0.77. Its wing allows to be added to a new center section. Note that the An-225 is not as thoroughly optimized as other heavy transports; for example it does not have leading edge devices on the new center section. I guess the Ukrainians simply allowed themselves a few shortcuts when the An-225 turned out to be good enough for its intended purpose (to transport Buran).

wdym "no increasing root chord"?

the sweep and the taper

"stuck to"?   Had to laugh at that though may be 100% true...  I'm thinking of buying a pot of glue and opening my own modification center...

@quietflyer. The SB-10 wing is made of 5 parts which can be taken apart for road transport. When being prepared for flying, the parts are stuck together. Literally. Did it myself often enough to be sure about this.

@Abdullah I mean the reduced TE sweep which is used on many swept wings but not on the An-124.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
What are the consequences of touching down at too low of a speed?
The consequences of a high speed touchdown / high vertical speed are very much obvious. However, what will the consequences be of a low speed touchdown? How severe are they (if any)?

Since you refer to "high speed touchdown / high vertical speed" together separated by a slash, I'm wondering if I'm correct in interpreting what you mean is a high airspeed at touchdown accompanied by high vertical speed? And if that is correct, do you mean that the two always go together?

@terry I am not sure if my question is clear that's the reason for the slash. I am aware that those are two different parameters with different consequences and level of risk. I basically want to know the opposite. i.e. what are the consequences and risk of a low speed touchdown. (if any)

This is certainly not a comprehensive answer but can get you started. I’m assuming fixed wing non-VTOL aircraft.
A low (forward) speed touchdown, all other things being as close to nominal as possible in that scenario, translates in all likelihood to a steeper than normal landing and can be associated with loss of sufficient lift or even stall and can result in a hard landing or crash. If trying to compensate for loss of lift, the same scenario will lead to a higher pitch than normal and thus add (or replace the above with) a tail strike risk.
A low vertical speed touchdown, all other things being as close to nominal as possible in that scenario, means a shallower trajectory than normal and can be associated with a long flare or a deep landing and as such poses risks around stopping performance (e.g. if the touchdown is so soft that the automatic deceleration systems don’t even realise the aircraft is on ground) or available stopping distance (if all the runway is used up trying to stick the aircraft down, none is left for rollout). Exiting the runway down the far end at substantial speed again is a recipe for significant damage and danger for life.
A touchdown with both (too) low forward and (too) low vertical speed doesn’t really exist, as that would mean a touchdown roughly along the nominal path but with lower speed, and since approach speed is usually calculated to be somewhere around minimum safe speed (i.e. stall speed plus some margin), slowing down significantly means stall, at which point the scenario changes to low forward but high vertical speed at touchdown.

This answer is great but I'd like to add one thing: Low speed at touchdown, depending on how low it is, can lead to a tail strike, because obviously you need a greater pitch angle to avoid a hard landing. Not a great thing if you don't want to lose your job :)

Thank you for your views. Yes the assumption is correct - just neglected to mention the a/c type. Would a hard landing not be associated with a high vertical speed and higher (forward) speed? Which may result in a longer flare and possible rwy excursion? Would a lower speed at touchdown not be beneficial esp with regard to available rwy and stopping distance? Esp when one would require an early turn-off to accommodate another a/c on a single rwy airport? I dunno if my explanation or interpretation makes sense - i don't know how else to put it...lol

@lemonincider Thank you, great point. Added!

@MarshallinoCoetzee Well, sort of. Your first point can occur, too. Both with an early flare (bleeding off too much speed) or a late flare (not pulling off enough sink rate) you can get a hard landing. Generally, we would not associate hard landing with an increased overrun risk, though, as long as the touchdown is in roughly the right place and the aircraft remains halfway functional. If the speed is too high to begin with, and with a normal flare, it’s more likely the aircraft will float forever rather than touch hard. All in all, there’s more ways to mess up a landing than to get it right!

@MarshallinoCoetzee Low speed at touchdown makes all kinds of sense, among others for the reasons you list. However, as I said in the answer, generally landings are flown somewhere around lowest safe speed already. Consequently, approaching at lower than normal speeds is eroding safety margins and, the slower you get, first increasing then rapidly decreasing the likelihood of experiencing a landing to remember.

I'm going to assume "low speed touchdown" means making ground contact at a slower airspeed than normal. Insofar as it can be done safely, slower=better; less energy to dissipate, shorter landing distance etc etc.
"Can be done safely" is the key phrase.  Propeller driven airplanes, especially those that are designed for Short Take Off and Landing operations, can use high lift devices and power to slow to a lower airspeed than normal in order to touch down at the lowest possible speed.  It's a specialized procedure because there are some risks; the power is being used to manage sink rate and quite a lot of if is required to overcome all the drag of a slow speed STOL approach. Also you are closer to stall speed.  There is little margin for error if something goes wrong with that power.  The result, if things go off the rails, is a high sink rate touchdown which may or may not damage the airplane. But, you are doing it on purpose and you accept the risk.
Aside from that kind of specialized technique, "lower speed than normal" (as I would phrase it) at touchdown is not a good thing to strive for because the aircraft needs to have a margin of surplus energy through the landing flare to allow the pilot to regulate sink rate without power in the final seconds.  That is, when you flare for landing, you are trading inertial energy for increased lift (pitching up during the flare) to reduce sink rate and manage that sink rate until the touchdown. This is especially true for jets, where you generally can't use power through the landing flare as you can with a propeller airplane, because engines must be at idle before touchdown for the lift dump system to work properly.
So if you are slower than you should be, there is very little surplus energy available and if high sink rate develops there is no way to reduce it (it's too late for power to help).  Especially in a jet, you don't want to be much below "reference speed" (full flap approach speed) when you start the flare because at that point, with engines at idle, you are touching down no matter what and if you are too slow, some or all of your intertial energy surplus is gone and the pitch up during the flare may not slow the sink rate at all.  Then it's BANG, and off to maintenance for a hard landing inspection.  Some jets are more forgiving of being under-speed than others.  Those with slat systems and multi element flaps are quite draggy in the landing configuration and bleed energy very fast. Cleaner jets with hard leading edges and simpler flap systems can be actually a bit more forgiving of being too slow because they don't decelerate as fast when the thrust is brought to idle.
Large turboprops are different in that power from that big propeller disc has a huge direct impact on sink rate and on deceleration, and on some you carry power right into the landing flare and may use the feathering off of power to control the touchdown (you land a Q400, which has limited nose up pitch angle, that way). Even there though, if you are too slow, high sink rates may develop that you can't catch in time, and wham.
So bottom line I guess is, there is a sweet spot speed for each airplane to be able to land as slow as possible while still having adequate safety margins via a little bit of surplus energy, and the main penalty for failing to observe that speed is high sink rates resulting in hard landings.

There are other reasons for varying approach/touchdown speeds.  For instance, you might be landing on a rough dirt strip, and want to touch down as slowly as possible to minimize stress on landing gear.  Or you might need a steep approach to avoid hills or tall trees...

Yes if you are doing it on a propeller aircraft you will slow below normal approach speed with large amounts of power to arrest the sink.  That's a STOL approach.  You know going in that if the engine were to quit while doing so, if you are too close to the ground to dive for speed, you are screwed.  You are going to hit hard.   You can't do that at all in a jet unless you plan to crash.


text:
How do I fly a direct entry holding pattern when approaching from an awkward angle?
If my course lies anywhere within 30 degrees adjacent to the 'direct entry' sector borders, do I fly the holding pattern as depicted below?

Very good video on MzeroA.com about this.

To add to Michael Hall's answer, the direct entry is the one where you get straight on to the "racetrack" with minimum maneuvering and that is possible from anywhere within the direct entry sector.  The other two entries involve initial maneuvering "off the racetrack" so to speak.
That entry diagram is a procedural convention, not a hard regulation you must follow exactly.  The whole area is protected airspace, so it's not all that critical that you fly exactly this or exactly that as long as you stay in the protected airspace. You'll get dinged on a check ride for using a bad entry (using a sector's procedure while significantly outside of the boundary of that sector), but ATC would never bust you because you didn't follow the entry protocol perfectly, as long as you didn't leave the protected airspace and you got established properly without too much meandering around.

The answer is yes, you would enter holding just as you depicted.


text:
Is drag higher when flying in a crosswind?
Is this true that during a flight with a crosswind the drag increases due to the fact that the relative wind blows at a certain angle to the aircraft's nose but not precisely in the opposite direction to its flight path as it would be without a crosswind?

Please give words to the labels in the diagram.

Yet another suggestion-- it is normal to draw the arrowhead at the front of the vector, not in the middle.  Drawn in the middle it looks sort of like you are adding two vectors together in each leg.  Likewise avoid the multiple arrowheads on some of the vectors.  But the main thing is to draw the "relative wind" arrow equal in length and opposite in direction to the airspeed arrow, The nose of the plane should be at point A, and the plane should be pointing exactly along the direction of the airspeed arrow.  The arrow on the left side.   Does that make sense?

In your example the ground speed is lower because the flight speed vector does not point straight to the destination. This might seem like drag is higher, but all that is higher is actual flight time to the destination.

If you flew it the whole way in a sideslip like your drawing shows, yeah, there'd be a drag penalty. You'd also be holding a bank angle the whole time.

No, it's not true-- have you ever seen a birds feather's blowing sideways?
We fly INSIDE of the wind, not AGAINST the wind.
You should draw the airplane symbol on the left-hand leg of the triangle, pointing in the same direction as the left-hand leg, and you should draw the "relative wind" arrow equal in magnitude and opposite in direction to the airspeed vector, i.e. the left-hand leg of the triangle.
Consider the fact that many of us have had the experience of actually BACKING UP in flight, relative to the ground.  Now, do you think the air was flowing backwards over the wings?

Is this true that during a flight with a crosswind the drag increases due to the fact that the relative wind blows at a certain angle to the aircraft's nose but not precisely in the opposite direction to its flight path as it would be without a crosswind?

Nope. Normally, pilots maintain coordinated flight. This means that they always point the nose of the aircraft directly into the relative wind, regardless of which way the wind is blowing.
(During straight and level flight, keeping the nose pointed into the relative wind is easy. For the most part, the vertical stabilizer does it for you.)
The aircraft's actual flight path is totally irrelevant to aerodynamics. In other words, the plane doesn't know or care what the flight path is. The flight path affects one thing and one thing only: the motion of the ground underneath the aircraft.


text:
What are the rules for flying drones in National Recreation Areas?
National Recreation Areas allow powerboats on lakes and roads for vehicles, so can drones fly in this area? Can model aircraft fly in this area? Can model boats be used on the lakes or rivers? Can rafts be used in the rivers?

The first 2 questions may attract an answer, but I'm not sure the use of model boats or rafts is on-topic for an aviation forum.

The operation of UAS in these areas is regulated by the National Park Service, but, according to a 2014 memorandum, this authority has been delegated to the individual parks themselves.  You would have to check with the park itself.  Further information is available in an NPS article on the topic and in the NPS rules and regulations section.
For an example on the state level, the Pennsylvania Dept of Conservation and Natural Resources has designated flying sites in six flying sites at a selected number of state parks.  If I go to the website for the Allegheny Portage Railroad (a park managed by the NPS), they have a specific statement on UAS usage in their policy compendium.
Boats and such...that I'm less sure of.


text:
How can you calculate the vertical speed of an helicopter during auto-rotation?
How can I calculate velocity of a helicopter when it falls with autorotation when the engine fails, given all the parameters such as mass , height , wing size etc.

Neglecting drag, pretty much everything falls at 9.8m/s/s

is lift force a parameter?

look at the VSI? :-)

It would depend on the pilot's inputs, since autorotation is still controlled flight and the pilot could choose to descend faster or slower. Depending on the helicopter, there may be a trade off between the amount of time it takes to descend and the distance covered. For example, the sink rate of the best ratio of forward distance covered to vertical distance covered (equivalent to glide ratio in a fixed wing aircraft--the engine failed over water and the pilot wants to go as far as possible toward land) could be different than the minimum possible sink rate (the engine failed over a safe place to land and the pilot wants to buy time while trying to restart the engine).
The most important quantity that affects minimum sink rate in either case is disk loading, which is the equivalent of wing loading in fixed wing aircraft. Page 4 of this pdf (heading: "Basic Physics of Autorotation") has the information you need to calculate minimum sink rate during autorotation based on an assortment of parameters.


text:
What constrains a paraglider vertically?
I recently flew on a tandem paraglider for the first time. Since then I keep asking myself a question I have no clear answers to.
While flying I clearly perceived the lift generated by the airfoil, but the strongest feeling I had was as if the paraglider hung to a rail, like a suspension railway, or to a cable, like a cable-car. In other words, I perceived a very strong vertical constraint. I know the airfoil generates lift, but I understand the amount of lift is not enough to give you a stability feeling like when driving a truck! To be similar to the constraint produced by a rail, this vertical constraint should be in the order of thousands of kg, IMHO.
Any suggestions on how to estimate this amount, and its origins?

Let me paraphrase this question a bit: by "constrained", I believe the OP means "very stiff". The acceleration is sudden - e.g. it goes from level flight to ascending flight in a very short amount of time, as opposed to, a general upward acceleration (and associated increase in G loading) lasting for 10 seconds.

What you perceive as "motion" is acceleration.
No acceleration, and you feel no "motion" -- your kinesic sense and inner ear will tell your brain you're sitting still on a solid surface.
What you experienced as "vertical constraint" was nothing more or less than the result of flying in a very stable manner relative to pitch -- no pitching, up or down, means no change in vertical acceleration (which ought to be exactly 1 G at all times, if you're to feel "still"), and no sensation of motion.

To be similar to the constraint produced by a rail, this vertical constraint should be in the order of thousands of kg, IMHO. Any suggestions on how to estimate this amount, and its origins?

The thing is that the constraint is something you "perceived":

I perceived a very strong vertical constraint

not that was actually there.
Only gravity, lift, and drag (and thrust, if powered) are acting on the paraglider, nothing else.
And the lift is easily estimated, as it is roughly equal to the weight of the passengers and the aircraft summed up and being this a paraglider, definitely not in the range of the thousands of kg.
Having this been your first experience, the sensation can easily be explained by your lack of familiarity with the transportation method.

Fundamentally, the "constrained" feeling comes from the steepness of the lift coefficient vs angle of attack curve.
The angle of attack is the angle at which the air approaches the wing. In level flight, this has a certain value, let's say around 5°. Now let's say you encounter a rising pocket of air. Instantaneously, the angle of attack increases. This directly increases the lift coefficient. As a result, the aircraft starts accelerating upwards, until it is ascending as fast as the rising pocket of air, at which point as far as the aircraft is concerned it is in level flight again (while it is in fact rising along with the air pocket). The "sharpness" at which this happens is your "rail-like" feeling of "vertical constraint" as you call it.
For thin airfoils, the lift coefficient is approximately $2\pi \alpha$ with $\alpha$ the angle of attack. That means that if we were in level flight at $\alpha=5°$, we would be accelerating upwards at $1g$ if the angle of attack increased to just 10°. I can promise you that you can't tell such a minute change in the angle of the incoming wind. Therefore, as far as you are concerned, the wind is always coming head on and you feel like you are flying "on rails".
By the way, "thousands of kilos" of lift for a tandem paraglider of let's say 250kg would mean over $4g$ of acceleration which would be enough to knock you unconscious if sustained for any amount of time.


text:
How can I find which engines are used on the different A320 weight variants?
When looking in the type certificate for the different configurations of the A320, I found a lot (really, more than 50) weight variants listed. But none seemed to mention the actual engine paired with that specific weight variant. Is there something I am missing, or is there another way of finding out?

I've found mention of weight variants in this document.

Each section will list the specific models that it applies to. For example, in the Maximum Certified Masses section for the A320 (1.III.13), you'll see the first section applies to the A320-211/A320-212/A320-231, and it lists the 19 variants of these models.
Next you consult the engines section (1.III.5), which will tell you, for example:
A320-211 - Two CFMI CFM 56-5A1 jet engines (MOD 20141), or CFM 56-5A1/F jet engines (MOD 23755).

Right, that makes sense. And the different weight variants are the "name" of a specific combination of e.g. fuel capacity and onboard equipment, I guess?


text:
Does Raymer's installed engine equation include the weight of the pylon?
I am currently modelling an aero engine and require the weight breakdown of the individual components, I have the dry weight of the engine and need to verify the pylon and nacelle weight.
Raymer has presented an equation for the weight of the installed engine in his book
$$W_{InstalledEngine} = 2.575 *(W_{Engine})^{0.922}*N_{engine}$$
Does this include the pylon?

The equation is probably a (nonexact) curve fit to some data. So you have some variation around the equation to start off with. The error from the pylon (either way) weight could be insignificant, so you might as well ignore it. Just my opinion.

Nengine is the number of engines on the aircraft.

No, it doesn't include the pylon. If you think about it, the engine is installed on the pylon, which is part of the aircraft's fuselage or wing structure and not part of the engine.
You can see what I mean by watching this video of the replacement of an engine on an American Airlines 777.
Raymer's equation does include the nacelle and other auxiliary equipment installed on the engine.

I do not have access to Raymer's book, only to Torenbeek. Section 8.4.2 states:

Thus a specification of the definitive engine weight $W_e$ is usually available comprising:

engine weight, bare and dry,
standard engine accessories and
additional weight contributions such as gas generator cowling and/or noise suppression material.

Since the pylon is not listed there, we can safely assume that pylon weight is not included in $W_e$


text:
What is this twin engined jet?
I was barely able to get a shot of this plane so it's not great quality. I was hoping someone could identify it for me. I've never seen one like this.

It's one of NASA's three WB-57F aircraft attached to Johnson Space Center in Houston, Texas, and operating out of nearby Ellington Field Joint Reserve Base. The B-57 was a tactical bomber that first flew in 1953, and the WB-57F was a modified version that the US Air Force used for strategic reconnaissance. The three aircraft with NASA are the last flying examples of the type and are used for Earth science, and are very versatile as they can fly up to 60,000 feet or higher.
The image below from Wikipedia shows one of the aircraft with pods on each wing.

Source


text:
Where do standard torque values in maintenance manuals come from?
Maintenance manuals of today's civil aviation aircraft (from both Boeing (e.g., B-737) and Airbus (e.g., A320)) have special chapter to describe "standard torque value" for fasteners and connections. These values are determined by material, size, etc.
I wonder where and how these values come from. Could anyone provide me with detail about this?

The standardized values are related to the yield strength and elasticity of the fastner.  Bolts in normal tolerance holes are effectively spring clamps (bolts in close tolerance holes can be better thought of as spring clamps + shear pins) and when you are tightening a bolt you are using a spiral wedge, the threads, to force the bolt to stretch to clamp the parts together.
You want to be able to stretch the bolt to apply as much clamping force as possible without exceeding its yield, or permanent deformation threshold.  It's like stretching a spring too far, so that when unloaded, it is longer than before.  You would say that the spring is ruined if that happens.  Same with a bolt. If you overtorque it and exceed its yield strength, it will be a bit longer than before when loosened and will have lost some of its ultimate strength after being permanently elongated.
So the standard torque tables are limits on how much the bolt can be stretched, converted to the equivalent rotational force applied to the spiral wedge of the threads.  The values are those that keep the axial tension force below the yield threshold, with some safety margin.  The standard limits are a function of the material strength and elasticity of the material that a particular bolt is made from.
A lot of the time torque values are given that differ from the standard values because the designer wanted to customize the clamping force for some other purpose, such as to limit clamping force on the base material or gasket or washer, or limit shear loads on parent material threads (like a steel bolt in an aluminum casting).  The normal engineering practice is to quote a torque value on the engineering drawing (and hence in the Maintenance Manual procedure) when it differs from the standard tables.
So as a general rule, when a torque value is from the standard torque tables, it's a limit for the bolt itself and is related to its tensile yield limit.   When a special torque value is given, it's a limit to control force applied to something other than the bolt itself for various other reasons.

This may be worth a separate question, but when the issue is the tensile yield limit of the bolt, is it a matter of what the shaft can withstand, or the threads? In standard fasteners, is the thread pitch and depth, and length of the nut, specified such that the shaft would fail before the thread gets stripped?

Depends on how many threads are in the female element to distribute the shear loads on the bolt threads.  A nut that is designed for tension loads will have enough threads distributing the shear force to have a total thread shear strength that is higher than the tension yield limit on the bolt.  Aircraft nuts designed for tension are fairly deep. Nuts designed for shear applications only are shallow and are not torqued very high, like the nut on a bolt that acts as a shaft for a bellcrank. Yield shear strength of threads are usually limiting when a steel bolt goes in something soft like alum.

+1 I want to add something about thread geometry - but I don't know where to edit it in. For the different geometries there might be some that seize (self weld) at some torque and you want to not exceed that. There are also tapered bolts which will have a torque based on the compressive strength of the material, not the tensile.

Fasteners have been standardized by the ISO. These standards cover e.g.  bolt sizes, thread pitch, and material grades.
This ensures that bolts made in factory A fit nuts made in factory B, for all factories worldwide. It also ensures that when you buy a bolt, you can expect it to behave a certain way: a bolt of size X and grade Y will be capable of at least force Z.
ISO 898 defines material grades (called "property classes"):

For metric bolts strength is according ISO 898 Mechanical properties of fasteners made of carbon steel and alloy steel described by "property classes" with designations 4.6, 4.8, 5.8, 8.8, 9.8, 10.9 and 12.9.

This property class is usually embossed on the bolt head. Each property class has requirements for the amount of load a bolt can handle, etc.
The tightening torque tables are derived from these requirements: the torque in the table is typically calculated for bolts that are loaded to 75% of their tensile strength.

Who is responsible for making up these standard torque table?

ISO has set the material properties, but I haven't found a torque table as part of the ISO 898 standard.
There is an SAE standard torque table for aerospace applications: SAE AS 1310B-1996.
Unfortunately none of the ~6 torque tables I looked at for this answer provided their origin. There may be more standards.
Standard torque tables make some assumptions. One of these is that the object being bolted has to be strong enough to take the applied force.
And this is where the standard torque table feeds into the design process. Normally you choose a bolt size and grade depending on the materials you want to fasten (their material properties and thickness). It's then up to the manufacturer to either follow the standard torque table (which you want, because it's the easiest on the mechanics that will work on the aircraft), or to specify a different torque for an individual bolt.

Who is responsible for making up these standard torque table? ISO , aircraft manufacturer， fasterner/connections manufacturer， or other ognizations?

I've amended my answer.

Many thanks for your info!


text:
What are the roles of the co-pilot in commercial aviation?
I am currently doing a project(in college) on the history and future of the role of a co-pilot and to start it off I wanted to just summarize what the roles of the co-pilot are.

Welcome! It may be more complex than pilot vs copilot. A crew may be made of two captains (pilots). In a crew of two crew members, one is flying (PF) and one not flying (PNF) but monitoring. Both the captain and the first officer ("copilot") can execute each role (not at the same time). See here. In addition the captain (or one of the captains) will have the role of PIC (pilot in command), in responsibility of the aircraft and the safety of everybody. PIC may be PF or PNF.

I'm an airline pilot. I am a First Officer which means I fly that "copilot" role. The Captain makes the final decision and has the final responsibility for what happens, but I have an open forum to speak up and I stay on top of everything that's happening. We apply CRM and TEM, threat and error management together. As far as operational duties go, they are shared for the most part. Actions are usually divided into PF (pilot flying) and PM (pilot monitoring). Research the concept of CRM. Also look at Tenerife crash and how it changed cockpit culture.

Eastern 401 had a big impact on CRM too.

Firstly, "co-pilot" is not a term that is really used anymore. When people say that they usually mean the First Officer. It's a bugbear of mine because "co-pilot" implies that there is one real pilot and a half pilot, when the reality is an airliner needs at least two fully qualified pilots to fly it safely!
When it comes to actually flying the plane, the two pilots have designated roles - Pilot Flying (PF) and Pilot Monitoring (PM - sometimes this is called Pilot Not Flying). Both the Captain and the First Officer share these roles - usually one of them is PF on the outbound leg and the other one is PM on the inbound leg. The PF manipulates the controls to actually fly the plane, whereas the PM handles communications and other required tasks that don't involve actually flying the plane.
The biggest difference between a Captain and a First officer is responsibility. The Captain is the Pilot In Command (PIC), who has ultimate responsibility for everything that happens throughout the flight. There are some practical things that only Captains can do, like flying into some tricky airports, landing in strong crosswinds, and on many aircraft only the Captain can use the steering wheel (or Tiller) for taxiing.
Historically there was a strong heirarchy - the Captain was the boss and the co-pilot was, you could say, a servant. This posed big problems, because the Captain is not always right. The advent of Crew Resource Management (CRM) has brought this down to a much more desirable level - where there is still a heirarchy to ensure decisions are made, but not so much that they are unquestionable. The future of the First Officer role will be one of continuing to recognise that they play an important role in a functioning cockpit, rather than just there to serve the Captain. And hopefully people will stop calling them co-pilots!

" The Captain is the Pilot In Command (PIC)", not really, the pilot in command is whoever decides to take on that role and should also be shared between the captain and first officer.

@RonBeyer No I think you are confusing 'Pilot In Command' with 'Pilot Flying'. I've never heard of a First Officer being PIC.

@RonBeyer Captain is PIC (and signs the release) and FO is SIC. This is regardless of who is actively flying the airplane, which is alternated (at my carrier CA had 1st leg, then FO  flew the next two, CA the following two, etc)

Co-pilot does not imply half pilot...as the prefix co means "together, mutually, in common". Maybe the public thinks of it that way, but I don't think the word itself implies that at all.

@Prodnegel I see your point. But why have a pilot and a co-pilot instead of two co-pilots?

@Ben, That actually sounds like a great question to ask :p. Here is a cool link I'm sure you'll appreciate http://www.askthepilot.com/pilots-and-copilots/

Your question's title says "commercial aviation", and in the question you indicate you're interested in the history. With that in mind, I'll add to Ben's excellent answer.
Commercial aviation includes not just airline but also non-airline flying, including corporate flying. In corporate flying, the duties of the co-pilot varied greatly depending on what the equipment was, who the pilot was, and what company was operating the aircraft. I've deliberately used the pilot and copilot terms because prior to 1985 when I did my last corporate flying, I heard those terms more often than captain and first officer when it came to corporate work. The latter terms were "airline talk" to us, and using them for what we were doing seemed pretentious, although that was starting to change.
The typical corporate usage by small companies of small aircraft, including small business jets usually did not include carrying a flight attendant. That meant the co-pilot often did things a flight attendant would otherwise do, including mixing drinks before engine start and cleaning up vomit after the flight. I did both numerous times.
On the airline side and before proper usage of CRM, the first officer might be used as a scapegoat, especially in third world countries and in Asia. An apparent example of this was the China Airlines 605 accident at Hong Kong's Kai Tak in November 1993. Look at the transcript of that accident. The captain is P1 and is flying the aircraft, the first officer is P2 and is performing PNF duties up until 46 seconds before they hit the water. After that, P2 seems to be manipulating the controls. At the time of the accident, the assumption was the captain had handed control of the aircraft to the first officer when it was obvious they were going to crash. To the best of my knowledge that assumption was never challenged.

It seems like it's a bit of an overgeralization to say that the first officer used to be used as a scapegoat in third world countries and Asia. There's a reason a cockpit voice recorder is installed in airliners!

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What is the difference between a wing station and wing buttock line?
Can someone explain (with images) what the difference between a Wing Station and Wing Buttock Line is, in terms of aircraft structures location identification?
The text I'm reading states:

W. STA = A plane perpendicular to the wing set at 90 degrees to
  leading edge
WBL = A plane perpendicular to the wing and parallel to the body
  buttock line

This description has utterly confused me!

The wing stations are perpendicular to the leading edge. Wing station zero is typically where the leading edge meets the fuselage. Wing ribs are typically parallel to the wing station. On swept wing aircraft, this won't match the flow direction, but it makes design and construction easier.
The wing buttlines are parallel to the airplane buttlines, which run down the length of the aircraft. Wing buttline zero is typically where the wing meets the fuselage.
This means that, unlike with other sections like the fuselage, the wing stations and buttlines are not perpendicular if the wing has sweep.

Rough illustration of the wing vs. fuselage BL and STA. Not to scale.

All these years in the business and I had no idea butt line was short for buttock...


text:
What are those buttons pushed after thrust is set to max
If you see this video

  at 0:42 you will see both of the pilots pushed a button on the front panel.
can someone tell what that is and what it does?

They're starting the chronometer. This chronometer is displayed on the navigation display.
It lets them keep track of the time limit they are allowed to operate at takeoff thrust. The limit is 5 minutes normally extended to 10 with an engine failure. After this, they must reduce power to the maximum continuous thrust setting (MCT).
There is also a time limit between the setting of thrust and when the engine reaches commanded power. If it is too long, it indicates a malfunction and takeoff should be aborted.


text:
What kind of planes are on this old photo?
Not sure what kind of planes are on this old photo? Does anyone have any idea?

This is a formation of Curtiss-Wright AT-9s officially known as the Fledgling, but also known as the Jeep.
A high resolution version of the photo is available here: A formation of AT-9s over the Gulf of Mexico. USAF Photo
The National Museum of the US Air Force has restored an example painted to represent the aircraft in the foreground; more information can be found here: AT-9

That's the Curtis-Wright AT9 Jeep.
It was a trainer aircraft produced between 1941 and 1943.
See more information here: https://en.wikipedia.org/wiki/Curtiss-Wright_AT-9


text:
What is this piece on the Bell 206?
I asked this question which led to another question of mine, What it the long rod just past the top of the nose of the Bell 206B helicopter and what is it's purpose?

If you mean the blade looking things that angle forward (top and bottom), they are wire cutters. The idea is that if a low flying heli encounters powerlines, those blades will cut the wires before they catch in the skids or rotor.

The entire "wire cutting" system is not just the knife, there is an abrasive strip running between the two windshield halves that scores the cable first, then the knife cuts it.

woah! so cool! I never would have guessed

@mins Your link is dead. :(

If you are referring to the angled pieces above the front window, and below the nose; they are referred to as the WSPS (wire strike protection system). Designed to shear a line before it wraps around the landing skids or rotor.
Related post: Is special equipment required to perform high-voltage line inspections?

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What is the wire running from the CG to the tail?
I was looking at airplanes a while back and noticed that there is sometimes a wire running from about the CG near the wind to about halfway up the tail.  I see this more on 737s but I have also seen it on C130s.  What is this wire?  To hold up the tail?  I have seen: What is this wire going from mid-fuselage to the tail on this 737? but I am more interested in all of the other planes that have it too.  Are there planes that actually use guy-wires for support or are all of the wires I see antennas?

I saw that but I was more interested in the other planes that have it too..

Sounds like an HF antenna. It absolutely isn't structural, as neither of those aircraft needs guy-wires for structural stability. (You'd also expect to see it on every example, not just some, if it were required that way.)
This article provides a lengthy discussion of HF antennae, for those interested in going deeper into the subject.
This thread has a related discussion of why not all HF antennae are of the long-wire type. Essentially, newer designs often replace the long wires.

are there relatively modern planes that have guy wires?

@dalearn Guy wires? No. Aircraft structural engineering has advanced enough that internal structure is strong enough without the guy wires. (There may be some isolated case where they're still used, but generally, no.) As for the longwire HF antenna, a buyer can probably outfit his aircraft with one if he chooses; I don't know if there is ever an economic case to do that or not thes days.

While this is a bit remote from the long wire use, there are still visible antennas on aircraft, most of the time for special use. Radar, magnetic loops, gamma sensors, or even usual VOR antennas. That's still the same reason they are external: better reception.


text:
Will dual-learning in a glider make my airplane learning safer?
This question got me thinking, would attending gliding lessons at the same time as my airplane training make me safer in a small plane or microlight?

Yes learn both, but... not at the same time.  As Dave says, there are too many differences to be absorbing simultaneously.  It's like a new airline pilot taking a type course on a Dash 8 and an RJ at the same time.  It'll burn you out.
If all this is a hobby activity in the first place with no urgent time lines, drop the power training for now and go take a glider course.  When you have your glider license, resume the power course (in most jurisdictions you get a bit of credit you can apply to the power license).
Absolutely no question that a power pilot who learned to fly gliders first, and especially if they became proficient in soaring, will be a superior power pilot.  Without the engine there, you learn fine motor skills, control coordination, energy management and speed control, and the ways of the atmosphere, to a degree that a power student doesn't and simply can't.  It also helps to remove a lot of the terror at the thought of dealing with engine failures.  I learned power in 1975 and gliders in 1993, and wish I'd started on gliders first.
And you may just discover that soaring is the sport for you.  You have to try it and get into it, and experience the incredible rush of climbing at 500 fpm in a thermal without an engine, that you found by trolling the sky, or spotting a hawk and joining him (and seeing him just look at you and carry on as if you weren't there), that may be a struggle to stay in or may be an easy elevator ride, maybe for 30 minutes in the air or 4 hours. No two flights are ever the same.  The private owners at my club, on a good day, launch at noon or a little after, and come back at 3 or 4 or 5 pm.
Power flying is mostly enjoying operating a machine that takes you from A to B, or to go sight seeing, in really fun and novel way.  Soaring is flying as pure sport; a game you play with the atmosphere. Like sailing a catamaran times ten, vertically.  It may not be for you, but if you get into the game, it's like nothing else and it's worth going to find out.
Plus since you're aviating largely on solar energy and at non-profit clubs the instruction is free, it's somewhat cheaper lol.

"Absolutely no question that a power pilot who learned to fly gliders first, and especially if they became proficient in soaring, will be a superior power pilot." - Here I think of the pilot of the Gimli Glider, and of Captain Sullenberger, both glider pilots.

Yep.  Even with seemingly simple things like the relationship to pitch attitude and speed, which is simple in a glider without thrust to complicate things, is an easy transition later on when you add power to the mix and have to learn that "pitch+power=performance" stuff.

This answer has really motivated me to try gliding! The thing I worry about, is I've read gliding clubs expect you to spend the whole day there, rather than going, flying and getting home, like you do in a GA lesson.

Well yeah.  They function on volunteer labour and most clubs have duty rosters for essential functions like running the flight line, towing and instructing. Some clubs run a half day shift system and only expect you to be around for the hangar unpacking or the packing, meaning you can come in the am and leave after lunch or the opposite, but others expect you to be around all or most of the day.   Depends. You will spend more time on site per hour flown, but it's a social experience as well and that's part of the whole thing.

In a glider club you will be expected to spend quite a bit of the day there.  There are the gliders to get in and out, and helping to launch and move gliders on the flightline.  You may be sharing your instructor and glider with other students, so may be waiting for that.  But you won't be bored, and you'll meet people.  The club leaders and instructors are putting in a huge effort, all for free.  In many cases you're learning from people with massive experience in commercial and military aviation.  Join up, get involved, and become a glider pilot!

No it will make it more dangerous.  Gliders and powered aircraft have different flight characteristics. You will have learn how to handle two completely different machines.  You will have to develop muscle memory for two different types of aircraft.  The flight procedures for the two types of aircraft are completely different, different approach profiles etc. You will have a tendency to either handle the glider like a powered aircraft or treat the SEP like a sailplane, to stop this you will have to actively try to decide what to do rather than instinctively fly the plane.
Gliding is an excellent skill to learn and will improve your flying once you've got enough experience, but learning on two types that are so different is not a good idea.

This answer is pure opinion with no references at all.

So is the other one, but they are both valid answers.  What sort of references are you looking for?  Mishap statistics?  Studies?  I doubt anything exists that breaks training down like this.

Yes, I would prefer the answer be more clear about whether both is bad or just both at once, and try to reconcile how gliding training seems to help in cases like the Gimli glider.

@Harper It's too bad that gliding apparently doesn't help one's ability to convert between pounds and kilograms, though, as the Gimli Glider incident also demonstrates. :)


text:
Is ear protection necessary for General Aviation aircraft?
What would happen if someone flew a brand new Cessna Skylane/Caravan or a Robinson R22 without using earplugs or headphones? Would they get hearing damage or it would be just a little bit loud where communication with co-pilot need constant yelling? How serious ear damage is?

Related

I don't know anything about the damage but R22 without headphones is a no no if you want to communicate even with the person sitting next to you. It is really really loud inside. Dug Dug Dug Dug Dug

This study on cabin noise with experiments in a Cessna 172s and a Piper PA-44 got the following results (noise comparisons are mine):

Peak:

Without headset: 101.3 dBA = rock concert (not front row though)
With headset: ~88 dBA* = vacuum cleaner (old bag-style ones, not Dyson...)

Average:

Without headset: 86.26 dBA = heavy traffic (by the side of the road)
With headset: ~73 dBA* = cloth dryer

Those value are not terrible per-se but on the long term ear damage is very likely.

*The study found that a headset reduces the loudness by 13 dBA in average. The reduction should be even higher with a noise cancelling headset.

I think even quieter with noise cancelling headsets.

@CrossRoads of course. I have Bose's A20 and it's really really quiet.

And to think that when I started flying headsets were considered a luxury.  Feeling old...

You can now get ANR earplugs https://quieton.com/

I don't like sticking things in my ears. Over the ear protection is my preference. If you want them off quick, a swipe of the hand and they are off, or you can lift one off and listen to unmodified sound if you think you are noticing something different sounding than normal.

To give an indication: in industry (at least around here), everything over 85 dB(A) means you're required to use noise dampeners (headphones, earplugs, etc.). So doing this for a while may cost you a bit of your hearing and doing it often would cost you a larger chunk of it. Communicating with those noise levels is going to be a challenge and uncomfortable to say the least.

Yeah, an noise-cancelling headset provides waaayyyy more than 13 dB of attenuation. I can sit by the window right beside a GE90-115b at climb power with my QC35s and it's little more than a quiet hum. Of course, I take them off during takeoff because GE90s sound awesome when they spool up. :)

Worth noting that a lot of occupational health and safety bodies start worrying about exposure times when ambient noise levels start to hit 85-90dB.  This puts a 172 firmly in the "should start caring about hearing protection" category, particularly for longer flights.

FWIW a phone app I found to measure dB levels put rimfire rifles and pistols in the 95db-105db range, and I'd never consider shooting without hearing protection....   And constant, repetitive noise (like the drone of a engine on a GA plane) is worse at lower levels than "sudden and brief" noises like gun fire - check OSHA recommendations for factory workers, etc.  Even at lower dB levels that are hearing safe the constant noise can be physically and mentally exhausting, not exactly something you want when you are a pilot (I would think...)

To supplement Quentin's answer, the effects are accumulative and depend on the level of exposure.
Most of the noise in a cockpit is low frequency sound of 75 to 100 hz with a 4 cyl engine/2 blade prop or 100 to 150 hz with a 6 cyl and 3 blade prop.  Then there is the usual wide spectrum machinery noise and the white noise from the airflow.
Long term exposure above about 84 dB will create hearing loss. Short term exposure above 105-110 dB will create hearing loss of some amount after one shortish exposure, maybe only a couple percent, but repeat it a number of times and you start to notice.  If something makes your ears ring temporarily after, that's bad.
84 dB is about the level of driving a convertible with the top down at 70 mph (that came from research done in Britain on hearing loss from driving).  A rock concert is above 100 dB. Once reason concert sound levels are so high (besides the fact they are catering to foolish young people) is the sound guys themselves are half deaf (One of my children is a performer and musicians and sound techs in the last decade or so have finally started to take steps to protect their hearing).
Airplane noise levels vary  a lot.  The quietest aircraft are wooden ones, and composite ones, and ones with thick windshields and windows.
I'm in my early 60s with pretty good hearing below about 12 kHz, which is actually really good for my age, but with tinnitus that is a steady 10-12 kHz tone that never goes away, that I've had for many years but slowly gets louder as I age.  I've worn earplugs and/or headsets since I learned to fly in 1975 and I'm sure I'd be pretty much nearly deaf if I hadn't.  Tinnitus can come from things other than loud noise, so it may just be bad luck.
Today, I wear an passive noise reduction headset, with ANR added, AND earplugs, having become obsessive about avoiding more hearing loss and making my tinnitus worse.
Anyway, a one-time flight with no hearing protection for an hour, in anything that doesn't leave your ears ringing after, probably won't have any more effect than all the other loud noises you will be exposed to over the years.  It's repeated exposure.
So if you have no choice in the matter, I wouldn't be concerned about a one-time ride, but don't make a habit of it.  But you really should take earplugs with you, and if you are offered a headset and/or earplugs, you are crazy to turn them down.

So John, are you saying wear earplugs underneath your headset>?

I do, but I don't have the really high end ANR headset like the Bose or Lightspeed, I have an ANR conversion of my ancient set of Dave Clarks. I wear EPs under them because I like it as quiet as I can possibly get it, and you can hear the radio voice fine with earplugs in (I turn the radio a little bit louder).  For casual exposure it would be overkill.

Thanks John, I fly about 3 hours a week in a C42 and it hurts my ears :) Will try this

With a headset on?

Yes, club ones, not ANC and not exactly airtight :D I think they are Pooley models, about £100

Yeah wear earplugs under them.  I modify 3M Plug In earplugs with a few inches of lead foil tape, used for gold club ballast, wrapped around the blue plastic peg and covered with heat shrink tube. The lead attenuates low frequencies really well. Most of the noise you're being bombarded with is 60-120 hz.  Or search online for low frequency attenuating earplugs if you don't want to do that. Foam ones are better than nothing tho.

I measured levels in the cockpit area of a twin Cessna where the propellers were inline with the pilot to the left and right and levels were 110dBA where I would be sitting.  Levels were 100 in the back in the cabin.  Without headsets, it would be impossible to communicate with crew/passengers and I'm sure hearing loss would result.

If you're crew, you probably want to be wearing a headset for communication purposes.
For passengers, these airplanes were flown for many decades before headsets became common (even for crew, using the handheld mic and overhead speaker) and long-time instructors had slight hearing loss, but for the random person taking a scenic flight to look at leaves or property on an occasional basis, I think you'd be fine without hearing protection.

Many people don't wear earplugs to rock concerts. Many don't protect their ears when using saws and similar machines or when shooting just a few rounds. But people do get ear problems from that.

Comm's would be very difficult, and hearing would be damaged eventually (ringing in ears, like being at loud rock concert). 180 horsepower engine in R22 makes a lot of noise, then add in noise from props and blades, and radio over an overhead speaker is about impossible to hear.
Skyline has even more horsepower with its bigger engine. I think 6 cylinder.
Caravan, is that piston engine or a turboprop?
Noise cancelling headsets take out a lot of the low frequency noise, and make things so much more comfortable.  Mine are from headsetsinc.com, are not ridiculously expensive, and work great behind my 180HP engine, no mental fatigue from noise after a 3 hour flight with ATC chattering away the whole time (lots of comm's going on in the northeast with Boston, New York, Albany).

Do you have the Dave Clark retrofit kit from Headsets Inc? I have that kit in my DCs that I bought in 1976.

I have that in 3 older pairs that I bought in 1996 or so, and recently bought 2 new pairs from them with music input Jack and automatic battery box turn off. Older units that I did the replacement on myself are 20 years old now and need to be disassembled and rewired to some extent. Volume knob in one, 2nd has developed a loose ground somewhere, 3rd I haven't worked out what it needs yet.

I modified by DCs about 10 years ago but have never been able to compare them to modern dedicated ones like Zulu3s.  I did an additional enhancement on my DCs by taking the modules out and encasing them in several layers of lead tape, the stuff you can get at golf stores for ballasting clubs.  There is a detectable difference.

What does the lead tape provide?

Additional low frequency damping to make the ANR module's job easier.  I once worked on a DeHavilland Buffalo that had a VIP corporate style interior (for an Arab leader in the Gulf) and the inside of the fuselage was lined with a couple thousand pounds of a sound insulation with lead foil with foam on each side, glued to the interior structure.  Similar to what's inside the apron the dentist drapes over you when you get an xray.  The interior of this Buff was super quiet.

That lead padding has been removed in a lot of AL aircraft. Moisture would get underneath and cause aluminum corrosion. Fiberglass padding would do the same.  There are more aluminum friendly options available these days for in-cabin sound proofing.

Yeah but this airplane was operating in the desert.  I've never heard of this lead foil stuff used on other airplanes tho.  Very heavy.

Cessna's had it, I've read where plastic scrapers were suggested for scraping it off to prevent damaging the skin.

Yes they would get hearing damage.  In fact if not using active noise-cancelling headsets, it is wise to wear earplugs in addition to a headset.

authors: Vladimir F Героям слава


text:
Is mode C required for CVFR in Canadian Class B airspace?
(This is in reference to Canadian Airspace)
Can you fly in Class B airspace under CVFR (Controlled Visual Flight Rules) without a transponder with Mode c (altitude encoding) capability?
To enter Class B airspace you'd require ATC clearance to begin with, I'd assume if you didn't have a transponder with Mode C, they wouldn't clear you, but I'm not certain.
I'd assume aircraft flying under IFR would have this transponder with Mode C capability, but aircraft that typically fly VFR may not.

It looks like gliders and balloons don't need a transponder in class B, otherwise you need ATC's permission. From the CARs:
101.01:

transponder airspace means controlled airspace consisting of the airspace referred to in section 601.03, within which the aircraft
  equipment requirements prescribed in section 605.35 apply

601.03:

Transponder airspace consists of
(a) all Class A, B and C airspace as specified in the Designated Airspace Handbook;

605.35:

(1) Subject to subsections (2) and (3), no person shall operate an aircraft, other than a balloon or a glider, in transponder airspace,
  unless the aircraft is equipped with a transponder and automatic
  pressure-altitude reporting equipment.
[...]
(3) An air traffic control unit may authorize a person to operate an aircraft that is not equipped in accordance with subsection (1)
  within airspace referred to in section 601.03 where
(a) the air traffic control unit provides an air traffic control service in respect of that airspace;
(b) the air traffic control unit received a request from the person to operate the aircraft within that airspace before the
  aircraft entered the airspace; and
(c) aviation safety is not likely to be affected.

The vast majority of GA airplanes have Mode C transponders and when you ask for the clearance, you will be given a transponder code to squawk.  If you don't have one, you have a problem and you probably won't get a clearance except in special circumstances.  Not only do you need a  Mode C transponder, it has to be calibrated and certified every 2 years by an AMO.
You could call Terminal while still clear of the Class B, tell the controller you are no-transponder would like to go from A to B, and see what happens: the controller may let you transit by reporting position at specific points if the path is out of the way.  Or maybe not.
Better yet, call the applicable ATC unit on the phone and find out if you can get permission to transit Class B non-transponder for a particular reason.
As a general practice however, the answer will almost certainly be no.  Just go around or under.


text:
What is a "BEACON"?
What is the "BEACON" and its symbol meaning from the Jeppesen Manual in the picture below? Does it just represent the beacon light? I'm confused.

Actually, it is not the point. I also mentioned the word "beacon" with a red underline. How could you change my question? Please reset it to my format please.

Exactly that's what I want to mean. Because at the top of the right, you can also see my red underline for the beacon. I just also mention my red arrow cause it also contains a beacon too.

Thank you, sir.

I would assume the operable word is “unidentified” which means it’s not the airport beacon it’s some other beacon that they want to make sure you don’t confuse with the airport beacon.

In general, a beacon in aviation is defined by ICAO Annex 14 as follows:

Aeronautical beacon. An aeronautical ground light visible
at all azimuths, either continuously or intermittently, to
designate a particular point on the surface of the earth.

What you show in the Jeppesen charts legend is the aerodrome beacon. The little star on the right (above the airport symbol) indicates that this airport is equipped with such a beacon and the symbol on the left will show the exact location of this beacon on the airport ground chart (typically located on top of the tower). Here is an example at Perth, Australia (YPPH):

(chart: Jeppesen, picture: twitter.com)
Why is it called unidentified? Because there are also identification beacons that signal a morse code to identify them. Regular (unidentified) aerodrome beacons just show a regularly flashing or rotating light.
ICAO Annex 14 describes the details:

Aerodrome beacon. Aeronautical beacon used to indicate the
location of an aerodrome from the air.
Identification beacon. An aeronautical beacon emitting a
coded signal by means of which a particular point of
reference can be identified.
[...]
5.3.3.3 An aerodrome beacon shall be provided at an
aerodrome intended for use at night if one or more of the
following conditions exist:
a) aircraft navigate predominantly by visual means;
b) reduced visibilities are frequent; or
c) it is difficult to locate the aerodrome from the air due to
surrounding lights or terrain.
[...]
5.3.3.8 An identification beacon shall be provided at an
aerodrome which is intended for use at night and cannot be
easily identified from the air by other means.

Note that there is also another type of beacon, the hazard beacon:

Hazard beacon. An aeronautical beacon used to designate a
danger to air navigation.

It uses this symbol on charts together with the altitude of the beacon:

Thank you so much, sir. This is one of the most explanatory answers I have ever seen. I express my gratitude. @Bianfable


text:
What are the meanings of the codes depicts in the square brackets? For example: [MDØ68]
I always see these codes inside of the square brackets with different charts. Especially I wonder about the meaning of Ø.

It’s just a slashed zero.

Thanx, but what about the whole meaning?

@pilot162 It’s the fix name.

Does Fix mean "A point" here? Could you be a little more descriptive? Sorry for my ignorance..

And as for why we need a slashed zero, is to avoid confusion with the letter O

According to the INTRODUCTION TO
JEPPESEN
NAVIGATION CHARTS on page 78

14 Jeppesen-derived database identifiers are depicted when different from State-supplied name.


text:
Is there research being done on light aircraft safety that involves a comprehensive flight protection system that adresses all risks?
Question edited for clarity, see below.
In 1998 NASA published the following:
"NASA's Aviation Safety Program: Making the Skies Safer
The goal of the NASA Aviation Safety Program is to reduce the fatal aircraft accident rate by 80 percent in 10 years, and by 90 percent in two decades. The ambitious $500-million program is a partnership that includes NASA, the Federal Aviation Administration (FAA), the aviation industry and the Department of Defense."
I am not sure if they have been successful. Is there any research being done into a complete safety system for light aircraft, from taxi out taxi in and engine shut down?
The goal of such a system the system is to protect the occupants of the vehicle through each phase of the flight. The aircraft configuration disuccsed is the typical 4 seater piston engined light aicraft.
The approach is a to assume that pilots will ake mistakes and need to have a second chance, provided through technology. Also, there should be a demarcation between accidents caused by error and those caused by negligence, and should be categorized and treated separately so as not to affect the accident record of genuinely safe pilots.
This question is somehwat related to
Would a roll cage plus a safety harness make a small GA aircraft accident more survivable?
Any aircraft goes through several phases of flight with its attendant risks.  I have listed the risks along with some of the risk - reduction strategies for each phase. Pilot training is important, and should take place in parallel, but pilots cannot be made error-free, and technology should be able to
protect them from the consequences (eg seat belts and air bags)
Take-Off run:
Running off the runway
Failure to stop after aborted take off

Proposed countermeasure:
Backup braking systems
Multi- wheel landing gear
Anti-lock braking
Retro - rockets for rapid braking
Crash protected structure as in cars with air bags and seat belts
Safety net at the end of the field as used in aircraft carriers in emergencies

Initial Climb:
Engine failure on take off
Loss of control - spiral dive
Stall
Stall and spin

Proposed countermeasure:
Advanced engine diagnostics including audio analysis of engine
Auto test of engines on start up
Automated flight envelope protection
Slatted wing for slower flight
Stall - resistant wing
Stall - resistant aircraft
Anti- stall parachute

Cruising Flight:
Engine Failure
Loss of Control / Stall/ Spin/ Spiral dive/ dive

Proposed countermeasure:
Advanced engine diagnostics including audio analysis of engine
Auto test of engines
Stall - resistant wing
Automated flight envelope protection
Whole aircraft parachute
En route safe landing areas overlaying GPS map
Automated emergency landing feature

Descent:
Engine Failure in descent
Loss of control

Proposed countermeasure:
Same as above

Landings:
Landing short of runway
Overshooting runway
Running off the runway
Stalling on approach
Hard landings/bouncing
Braking failure on landing

Proposed countermeasure:
Automated flight envelope protection
Backup braking systems
Slatted wing for slower flight
Multi- wheel landing gear
Anti-lock braking
Retro - rockets for rapid braking

Update: NASA is adressing some of these issues in its safety program:
http://www.nasa.gov/centers/langley/news/factsheets/AvSP-factsheet.html
Edit: The first answer by jwenting applies to the first part of this question, ending here. Also, the few comments given have been also very helpful in answering the original question. However I accept the question is too broad.
I will have to break this question up into several questions later. For now, narrowing the question down to be more specific let me ask the following question:
There are several measures mentioned above in the  many efforts underway to make  light aircraft safer, such as flight envelope protection, parachutes, Leaving cost aside for the moment, are these measures sufficient to reduce the risk by a significant amount in all phases of flight or are there any areas that these researchers have missed, for example?

I'm not sure where the question is here. You've listed some risks, but the set of all risks is effectively infinite. There are, of course, various ongoing efforts to improve safety. Some aircraft have certain safety features that are intended to address certain risks, but it's impossible to even enumerate every possible risk, let alone develop a specific countermeasure for all of them, and every new feature you add can increase risk as well (e.g. you add a parachute or airbag, what if there's an uncommanded deployment? or what if pilots take greater risks as a result of that feature?)

To add to @ZachLipton good elements, dependency on a safety measure is itself a risk, e.g. locking the door of the flight deck as demonstrated in a Germanwings accident. You need to think risks and countermeasures as a compromise that you believe will be "positive enough" without costing too much. It's not different from drugs. Accidents in aviation are already at a very low level, and going further is likely a matter of increasing flight deck automation, a known risk by itself. If you think about it, it's the passenger who slows down safety by demanding prices always lower.

Addressing all of these would make GA aircraft magnitudes more expensive. Most of your "proposed solutions" (other than retro-rockets and multi-wheel gear) already exist for GA aircraft as an option. "Flight envelope" systems in the form of AoA indicators, advanced engine monitoring, ballistic recovery chutes, even passenger airbags.

I'm not sure what you're asking here. There's always research going on into GA safety and as others have said, many of the solutions you've mentioned are already available in certain aircraft, e.g. Cirrus has a parachute, a stall-resistant wing and a 'panic button' to level the wings. But they still crash, often because pilots make bad decisions. If you can find some way to make your question more specific or limited you might get a better response.

As Zach says, it's impossible (and IMO not even desirable) to remove all risk.
Not only is the number of potential risks infinite, but the cost to counter even a small subset of them would be infinite as well.

Just one small example, from your list of proposals:
Say you fit a retrorocket that is supposed to stop the aircraft on an aborted takeoff if the pilot fails to apply the brakes.
Now, what if that retrorocket also fails? You'd need a backup for it, and a backup for the backup, ad infinitum. What if the retro fires and the kick is too much, injuring the pilot? So you'd need some way to shield the pilot from any impact at all, infinitely thick padding comes to mind. But what if the retros misfire and he veers off the runway into a drainage ditch, ends up under water? So he needs a breathing aparatus as well, with an infinite supply of air because you can not know how long it will be before rescue services arrive.

Not just would this be impossible to implement, but even if you could the aircraft would become infinitely large and infinitely expensive.

And as is shown time and again in human history, if you design systems to reduce risk, some people just get more reckless. When seatbelts were first introduced people started driving faster, especially taking corners at higher speeds, feeling invincible with their better protection. Not many people, certainly not most, but enough that accident statistics showed an increase in serious accidents with death or serious injury as a result. Same when airbags became mandatory.

Seems humans need some measure of inherent risk in activities, just to keep them from doing stupid things due to feeling invincible and able to get away with anything.

Thank you, I think the question needs to be broken up into parts, will do so.  Two additional sources of information : http://www.diamondaircraft.com/about-diamond/safety-features/ and http://archives.pr.erau.edu/highlights/CrashInjuryResearch.pdf and just search using the term "aircraft structure crash research"

@stackex555 not just that, the wording also needs a major overhaul. "all risks" can never be addressed for example, for the stated reasons.

jwenting, thanks, I have asked a more specific question with better results all around.  http://aviation.stackexchange.com/questions/32399/risk-management-in-single-engined-piston-aircraft-flight


text:
Can legislation help prevent CFIT or will it restrict freedoms too much?
Apparently in Australia there are penalties for a student flying in clouds.
Could penalties for flying IMC without an IFR rating reduce Controlled Flight Into Terrain (CFIT) accidents? Is it too much a restriction of freedom?
Would requiring pilots who fly into such conditions to declare an emergency and land at nearest airport be an effective way to prevent accidents?

As I understand it, flying into IMC when not equipped/rated nearly always results in UCFIT (uncontrolled) rather than CFIT.  CFIT occurs because of failure of navigation when IMC.

I'm a bit confused by your question. Entering IMC without an instrument rating is already illegal in the US (for example). Are you suggesting that pilots should be allowed to do it anyway, in the name of personal freedom? Or are you suggesting additional regulations of some kind?

Individual freedom must sometimes be limited for the interest of the community. That's the principle underlying any law in republics.

How do you enforce it though? Clouds don't show up on ATC screens, so without somebody nearby witnessing it, or self-reporting, nobody is going to know. As Pondlife said, some (many) countries this is already illegal, but you usually only get into trouble when it results in an accident. Even pilots who contact ATC for help getting out of IMC are rarely punished (in the US), even though it is illegal to get in IMC without an IFR rating.

Also, declaring an emergency if you get into IMC as a VFR pilot is a good thing, if there are ATC services available of course. Landing at the "nearest airport" however isn't. The biggest thing you want to do when you get into IMC is to get out as quickly as possible. Sometimes this means climbing through a cloud layer, turning around, etc. The nearest airport is probably just as socked-in as you are and landing in IMC is probably worse than flying in it.

Flying into mountains is already illegal. It still happens from time to time.

Simon, thank for the correction, yes the issue is that pilots lose control when flying into IMC when not equipped/rated. Pondlife, despite my searches I was not able to find anything that said that entering IMC without an instrument rating was illegal - none of the videos I watched stated that either which is puzzling. All around great answers, thanks.

I will let the questions and answers stand as they are, as there is much useful information there. If necessary I will formulate a better question along the lines rules of the help centre- :Search, and research
Be on-topic
Be specific
Make it relevant to others
Keep an open mind

The US regulation is 14 CFR 61.3(e): "No person may act as pilot in command of a civil aircraft under IFR or in weather conditions less than the minimums prescribed for VFR flight unless..."

Short answer: no.  Rule don't prevent accidents by themselves.
It is in choosing to follow, or not follow rules, that accident prevention is aided when a safety rule is put into place.  There are already ample rules about flying in instrument conditions and what the requirements for doing so entail.  Whether or not there is a penalty for a rule does not by default dictate whether or not a given pilot follows those rules.
Following those rules helps to prevent accidents.
Breaking those rules increases the risk of an accident.

Would requiring pilots who fly into such conditions to declare an
  emergency and land at nearest airport be an effective way to prevent
  accidents?

Simply having that requirement would not have saved JFK Jr's life.  It takes decisions on the part of a pilot to fly safely.  Your reference to "personal freedom" in this question is a non sequitur.

I'm going to start by rejecting the three major premises of your question:
First, Your "personal freedom" in this case is already restricted by regulation.
Whether a penalty is assessed for each violation of this regulation does not remove or change restriction - You are prohibited from flying into clouds without an instrument rating, just as you're prohibited from throwing your empty soda can in the street because of laws against littering.
The fact that you might "get away with it" because penalties can't be enforced for every occurrence does not remove the fact that there is a legal restriction.
Second, inadvertent VFR into IMC is, by definition, an emergency - particularly if you are not an instrument-rated pilot.
Prudence already demands that a pilot in an emergency situation declare that emergency, and then use all available resources (including ATC assistance) to ensure a positive outcome.
A regulation saying "Pilots entering clouds without an instrument rating must contact ATC and declare an emergency" would be redundant, and ultimately you couldn't reasonably enforce it (you would have to prove that the pilot flew into clouds and did not declare the emergency your proposed regulation would require).
Third and finally, while some VFR-into-IMC incidents result in CFIT accidents the majority of these incidents that end in an accident do so because of a departure from controlled flight, and are classified as "Loss of Control" (LOC) accidents.

To the meat of your question: Would enforcing penalties against pilots who inadvertently fly VFR-into-IMC reduce the CFIT accident rate?
Probably not.
Judging by this ATSB report on CFIT incidents the Australians don't consider the penalties to be a significant factor: The words "penalty" and "fine" do not appear in the report at all, and if they were a significant factor in cutting the CFIT accident rate one would expect them to be featured prominently.
Based on the answer you linked to the enforcement of this penalty in Australia is discretionary:

The regulations (CAR 172) effectively states that if you fly into cloud the penalty is 50 penalty points - I think each penalty point is currently 110 dollars so the answer to your question is you could be fined $5500. However, CASA uses discretion as to when to enforce this fine…

The system in the US is similar: There is a penalty of up to $50,000 (for individuals) for violations of the FARs and you may also face suspension or revocation of your pilot certificate, but this is pursued at the discretion of the FAA, and is rarely enforced in cases of inadvertent VFR-into-IMC.
The reasoning behind this discretionary enforcement (and general lack of enforcement against inadvertent situations) is that we know pilots who get in contact with ATC and seek assistance are more likely to have a successful outcome.
Consistently enforcing penalties against pilots who inadvertently fly VFR-into-IMC provides a disincentive to seek that assistance: "If I tell them what happened they are going to fine me lots of money!" versus "If I tell them what happened they're going to get me safely back on the ground."
The primary responsibility of the various aviation authorities is to promote safety, and penalties are used as tools to facilitate that. Where a penalty would provide a disincentive to safer operation it is often not used, and alternate methods of enforcement employed (such as education on the dangers of VFR-into-IMC and incorporating risk-based decision making into training programs).


text:
How is risk managed in single engined piston aircraft flights?
I have already read this post:  How dangerous is flying in a single-engine plane?
Recently as reported in the NTSB accident database, a pilot of a light aircraft encountered engine failure after take off. The pilot found no suitable area for performing and emergecny landing and deployed the aircraft parachute, escaping with some injuries.
It appears that some phases of flight of a piston single, there are sections of the flight for which safe recovery from an engine failure is not possible due to the lack of reachable emergency landing areas.
For example, after take off, the aircraft may be in a position that a safe landing and stop cannot be made with remaining runway. After take off, the pilot may encounter a heavily wooded or built up area, but a few minutes later may cross a highway or an empty field. In any case, his chances for safe landing keep changing throughout the flight, going from high to low to medium and so on.
Is it correct to say that this risk has to be taken, cannot be avoided?
Is it possible to reduce this risk with either better pre-flight checks and through purely technological means? Suppose I am taking flight instruction can I do anything to reduce the risk of engine failure?

Engine failures are already extremely rare as it is, largely due to the very strict requirements for maintenance and regular checks.

For most  pilots who fly well-maintained aircraft, mistakes, poor technique and bad decisions are much more frequent and important risks to consider than engine failure. That's not to say you should ignore the risk of engine failure, but you also shouldn't fixate on it.

The answers here are excellent.  To make a long story short, there are dangers in anything you do in life.  The thing to keep in mind regarding flying is the amount of care invested in safety.  That was the first thing I noticed in anything aviation; safety.  The school, the flying, the courses; everything revolved around safety.  If you invest time in aviation you'll find the same thing.  In fact, I would spend some time learning and getting closer.  Keep safety in mind and ask yourself after some time: was safety something important in what I've learned so far?  You'll be surprised at the answer.  You won't even believe you asked the question.
With regards to engine failure: if you ask a CFI he might tell you that he'd rather lose an engine in flight then lose an engine while driving a car.

"A ship in harbor is safe, but that is not what ships are built for."
You said in your question:

It appears that some phases of flight of a piston single, there are sections of the flight for which safe recovery from an engine failure is not possible due to the lack of reachable emergency landing areas.

This is true not only of piston singles, but also of anything that flies out of gliding distance of good landing sites - think about Amelia Earhart's Lockheed Electra.
You'll usually hear this called "inherent risk", but the correct term for the concept that you're describing is systemic risk. As you suggested in your question, this risk has to be taken, it cannot be eliminated.  The only way to eliminate it is to not fly; and sometimes, when the risk of the flight becomes too great, that's exactly the decision that a pilot has to make.

Is it possible to reduce this risk with either better pre-flight
  checks and through purely technological means?

Yes, as long as you're willing to pay for it. Everything in aviation is a tradeoff, and it's usually a trade either between safety and cost or safety and weight. As an exaggerated example, you could build a piston single with 30mm armor plating to mitigate the risk of incoming artillery fire, but it wouldn't fly very well and not many piston singles routinely take artillery fire anyway.
Those safety improvements which are simple and economical to make, we've already made mandatory (for example, all IFR aircraft certified in the USA need to have an alternate source of power for their artificial horizon if the primary source of power is electric).  Safety improvements which aren't simple or economical are left to the discretion of the owner of the aircraft.

Suppose I am taking flight instruction can I do anything to reduce the risk of engine failure?

Sure is.

Pay attention to your instructor and do what she tells you.  You can't prevent an engine failing because an oil pump blows out.  You can prevent the engine failing because you ran the fuel tanks dry.
Fly well-maintained aircraft. Talk to the mechanics who work on your airplane. Do what they say.  Avoid operators who let maintenance slide.  If you're the owner, don't let maintenance slide.
Fly aircraft that fly a lot. The worst thing for an aircraft engine is to sit in the hangar for three months, fly for an hour, and then go back into the hangar for three more months.  The more that engine gets used, the happier it is.
Have a contingency plan. For example, examine the area at the departure end of the runway and make a plan of where you would land in the event of an engine failure at any point before a turnback would be feasible. - Thanks Jonathan Walters!
If you do go down in a field, have a 24-hour survival/medical kit on board, and wear clothes suitable for the climate. Rescue doesn't get there instantly. Speaking of rescue, you did file a flight plan, didn't you?

One of the most significant things a pilot can do to minimize risk exposure associated with engine failure is contingency planning. For example, examine the area at the departure end of the runway and make a plan of where you would land in the event of an engine failure at any point before a turnback would be feasible.

Steve V's answer is pretty thorough but I'll just add a few items specific to engine failure on takeoff over a populated area:

Always do a thorough runup check. This can include a full-throttle static check.
Run through emergency procedures before takeoff. I do it while taxiing, verbally stating the steps from memory: EP1 (engine out over the runway), EP2 (engine out on climbout), EP3 (engine out at cruise). If you do have an engine out on climbout, you don't want to lose precious seconds trying to remember what to do.
Climb at or near Vx for the initial climb. It might only be the difference of 10's of feet, but that might be the difference you need to make it back to the airport or get to a field.
Know at what altitude AGL you could safely return to the airport. At some point the impossible turn just becomes a turn. 800 ft? 1000 ft? Go out to the practice area with an instructor and do 270 degree turns back at altitude to see how many feet you lose and how quickly it happens, in ideal conditions.
Always run the numbers. High density altitude? Near gross weight? Your climb rate will be terrible. How long will it take you to get to a safe altitude on takeoff?
Always be looking for where you'd put it down if the engine went out at that moment.

It's all about managing risk. Mitigating risk where possible and being prepared if something does go wrong.

Thank you for the answers, very useful and more or less completey answers the question.

Found some more information at these links: http://www.planeandpilotmag.com/article/some-thoughts-on-engine-reliability/#.WAR_cPmqqkp

That covers operational mitigation, but there is also design mitigation.  The biggest factor is the Part 23 requirement for a single engine plane to have a stall speed (Vso) no greater than 61 knots (70 mph).  that along with harnesses and seat requirements make crashes survivable if you keep the plane under control.  To quote the recently departed great Bob Hoover, "Fly the plane as far through the crash as possible."